Yeah, you could throw in some new wire, upgrade the caps, but you're still gonna have essentially an F30, you can't change the drivers or the box economically. My memory of the speaker is a bit wooly sounding, lacking in dynamic contrast, but a pretty pleasant speaker overall that should do very well in the rear channel. I don't know if it has any damping material (fiberglass) but if it does, try removing some or all of it to liven up the sound. A steel bolt or rod through the middle to brace front and rear panels may also help, not sure about the aesthetics though. At the end of the day the application isn't all that critical, so I'd try the more simple solution first. Best of luck with whatever you decide.
